Hi there!
In a future iteration of the game, I believe it would be convenient if players have the opportunity to select their desired player color (just like in the previous versions).
Nonetheless, since we do not yet have the possibility of choosing colors, I found somewhat of a workaround (when playing against AI).
At present, the colors have a predetermined position relative to the player slot:
- First slot: Blue
- Second slot: Red
- Third slot: Yellow
- Fourth slot: Green
- Fifth slot: Turquoise
- Sixth slot: Purple
- Seventh slot: Orange
- Eighth slot: Pink
Based on this insight, we can trick the system a bit. The lobby leader can specify which slots are allocated to players as well as which slots are allocated to AIs. The procedure is then as follows:
Step 1: Assign AI to all seven slots.
Step 2: Remove AI from the position of the desired color.
Step 3: Invite friend to the lobby.
Step 4: Repeat the above steps.
Step 5: Remove unnecessary AIs.
Step 6: Adjust the size of the map to fit the desired number of players. (Note, here I recieve the color pink even though I am now on the fourth position.)
I hope it can help you achieve your desired colors!
Now it’s the time for the Devs move 
